Image Acquisition Device Optical Path Difference Focusing
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Solution Overview
Problem
Conventional image acquisition devices face challenges in securing sufficient light for imaging while accurately detecting focal positions, as splitting light for focus control reduces the amount available for imaging, leading to decreased accuracy.
Innovation Solution
The image acquisition device employs an optical path difference generating member in the second optical path to form optical path length differences without splitting light, allowing for accurate focus control and securing light for imaging by synchronizing pixel column exposure with the rolling readout of the second imaging device, which calculates focus information based on contrast differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is split for focus control, then focal position detection is enabled, but the quantity of light for imaging decreases
Solution Approach 1:
The patent segments the imaging process into two distinct phases: a focus detection phase using a first imaging means with split light paths, and a main imaging phase using a second imaging means with full light availability. This segmentation allows focal position detection without compromising the light quantity for primary imaging by using different imaging paths for different purposes.
Solution Approach 2:
The patent introduces a beam splitter as an intermediary component that directs light to different imaging means based on the operational phase. During focus detection, the beam splitter directs light to the first imaging means; during main imaging, it directs light to the second imaging means. This intermediary mechanism enables selective light routing without permanently reducing light availability for imaging.
2Measurement precision
If light is split for focus control, then focus detection is achieved, but imaging quality deteriorates
Solution Approach 1:
The patent segments the optical system into a first imaging means for focus detection and a second imaging means for high-quality imaging. This segmentation ensures that the imaging function is not compromised by the focus detection process, as each means is optimized for its specific purpose. The second imaging means receives full light intensity without splitting, thereby maintaining imaging quality and reliability.
Solution Approach 2:
The patent uses the first imaging means to create a focus detection copy of the optical path, while the second imaging means handles the primary imaging function. This copying approach allows focus detection to be performed on a replicated optical path without affecting the main imaging path, ensuring that imaging quality is not degraded by the presence of focus control mechanisms.
3Illumination intensity
If rolling readout is used in the second imaging device, then light quantity for imaging is secured, but focus information calculation complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where image data from the rolling readout of the second imaging device is continuously analyzed to calculate focus information. The system uses the temporal and spatial information from sequential pixel column readout to determine focal position, creating a feedback loop that maintains focus accuracy despite the complexity introduced by rolling readout. This feedback approach enables the system to process rolling readout data efficiently without sacrificing light quantity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures a sufficient quantity of light for imaging while enabling rapid and accurate detection of focal positions, improving the overall imaging process by utilizing contrast information from the second optical path.
Implementation Method 1
an optical path difference generating member 21 for generating an optical path difference in the second optical image
Implementation Method 2
a photoelectric transducer constituted by a two-dimensional image pickup element such as a CCD area image sensor
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
In an image acquisition device M, an optical path difference generating member 21 can form an optical path length difference of a second optical image without splitting light in a second optical path L2. This can suppress the quantity of light required for the second optical path L2 to obtain information of the focal position, whereby a quantity of light can be secured for a first imaging device 18 to capture an image. The image acquisition device M synchronizes the movement of a predetermined part of a sample S within a field V of an objective lens 15 with rolling readout such that each pixel column 20b of a second imaging device 20 is exposed to an optical image of the predetermined part in the sample S. Thus obtained image data includes contrast information equivalent to that obtained when the focal position of the objective lens 15 is changed in the same part of the sample S, whereby the focus information can be calculated rapidly and accurately according to the contrast information.